I just ran into this problem with a new image I had created, instead of cloning from my previous images.
For me, it was a case of forgetting to apply the Microsoft Hotfix for the VMXNET 3 adapter when using Windows 7. All of my existing images already had this fix applied.
Your problem might be different, but here is what I found and how I fixed it.
When I took a closer look at the LAN adapters in the composed desktop, the LAN adapter name had a number at the end, indicating it was a new adapter and not a re-use of the base image's NIC. For example, the adapter name was Local Area Connection #2 or #3 or the active network name was my domain #2 or my domain #3.
To resolve the issue:
When I logged into the composed desktop, the network adapter no longer has a number appended to it and IPv6 is still disabled.
I learned about this Microsoft Hotfix from VMware KB article 2007319, which is not the same exact issue, but the Hotfix resolves the issue, at least for me it does.